Walls subject to horizontal loads such as water and earth pressure, wind etc. are traditionally constructed from plain or reinforced concrete cast in-situ or from steel sheet piles (see U.S. Pat. Nos. 3,316,721 and 3,492,826 for exemplary prior art structures).
The utilization of the materials in such structures is generally poor. Nevertheless, the economy of these traditional structures in many cases still compete favourably with more recent structures made from prefabricated reinforced concrete elements, chiefly, because the designs of prefabricated elements for walls generally are following the same basic shape of conventional in-situ cast walls -- with the corresponding consequence of uneconomical use of the materials.
Retaining walls are also known to have been made in reinforced concrete as folded plate structures approximately corresponding to walls made from sheet piles of the Larssen type. However, folded plate reinforced concrete structures of the said type have a number of drawbacks, the most important of which are the following:
1. The cross section and thus the effective depth is the same in all horizontal sections of the wall, although the requirement usually is an increasing effective depth corresponding to an increasing distance from the top of the wall.
2. The area of the concrete is the same in all horizontal sections of the wall, although the forces acting on the concrete are increasing gradually corresponding to the increasing distance from the top of the wall.
3. Different heights of walls require different sizes of folded plates, each size of which requires separate sets and size of moulds.
Accordingly, the disadvantages of the prior art are overcome by the present invention, through which novel methods are presented for producing retaining and other walls of different heights using a minimum of materials and using the same mould for these different heights of walls.
With this invention, a wall structure is provided having corrugations oscillating along a preselected axis line for the wall structure. While the corrugations at the top of walls according to the invention all are of identical size, the depth of the corrugations are increasing gradually towards the bottom of the wall. Also, the thickness of the front and the rear parts of the corrugations are increasing gradually towards the bottom of the wall.
In this way, the effective depth as well as the effective and structurally useful area of horizontal cross sections of a wall are increasing towards the bottom of the wall as is consequently the moment of inertia, which is a basic factor for the strength in any section of the wall.
Since the forces acting on the wall normally are increasing gradually towards the bottom of the wall, and since the materials are the better utilized, the more they are placed in the zones of maximum forces, the basic geometric shape as described above will represent a considerable saving in materials compared with a conventionally shaped, in-situ cast or prefabricated wall.
The basic corrugations of the wall may thus be sinuous, trapezoid and have any other basic shape, which form corrugations when linked together in a continuous band.
In spite of the varying cross sections of the wall, the basic geometry as described above may allow the front surface and the rear surface of the wall to be congruent or near-congruent. This feature greatly facilitates the production of the wall, especially when it is made from prefabricated sections, in the case of which the sections may be stacked as an integral part of the production process (as described in my copending U.S. application Ser. No. 483,444 filed June 26, 1974. Thus the handling and the transport of the wall elements are also made easier and more economical through the congruency of the surfaces.